Electric-contact thermostat.



STATES PATENT OFFICE;

G. omsmcm or Nnw Ycnx, N.Y., nssmnon 'ro THE rEoPLEs STATE. Buik,

* zrnusrnn,` or DETROIT, MICHIGAN, n conronn'rron or moment.

ELECTRIC-CONTACT THERMOSTAT.

Application illed January 18, 1918.1 Serial No. 212,808.

` To all fwltoin ittmcy concern.'

= SINGER, a citizen ofthe Unie-,d sont of America, residin at New York, in the county of New ork and State of New' York,4 have invented Vcertain new and use-A ful Improvements in Electric-Contact Thermostats, of which the following is a. specilieotion, reference being had therein to the accompanying drawings.

The invention relates to thennostets.of that type in which the electrical `contact is made or broken by the iateral deflection of an arched element in coperation with a. chord or tie element having e different ooeliicient of expansion. It is the object of the present invention to overcome certain defects of constructions of the type heretofore devised and to render the instrument more sensitive und Vaccurate in its operation and simple in its construction. The invention therefore comprisesV various features of -construction as hereinafter set forth.

In the drawings:

Figure 1 is a. longitudinal section through the instrument; 4 i

. Fi 2 is a slde elevation thereof;

Fig. 3 is a plan view. The principle on which the construction. is based is the deflection of the arch eicment by di'erentiel expansion due'solely to and the temperature which is to be controlled.

Accuracy is therefore only obtained where there is freedom formovement without frictional or other resistance; where the exponsible elements are exposed to free contact with the nir; and where the temperature of Vthese elements is unaffected either by independent heat generation or conduction to or from contacts other than that of the air. I have close-ly approximated the iden-l condition,-first, by eliminating friction and providing perfect freedom of ncti on without mechanical restraint; second, by providing .full exposure tothe :tir of `:dl the surface of the expunsihle elements, avoiding :my shielding of the one hy unothvr; third. hy providing suiiicient siren and mass in the element which forms n portion of the electrical circuit to quickly dissipute whatever heat is electrically generated; fourth, hy interposing thermal 'insulation between thel mounted to avoid transfer of heat from' the one to the other;A fifth, by providin 'a linkage between the elements having ill'erent coefficients of expansion, which secures accuracy in movement without necessitating a' high degree of mechanical fectiom n detail, A'is a. suitable o'r support, B and B are chord elementsparellelly nrronged in the seme plone and spwced from each other, lind C is theorch element arranged between the elements B and B and 1n substantially `the same plane and ving e eoeiiicient of expansion di'ercnt fro that of the chord elements. In the drawings the l curvature of this arched element is greatly i 'exag rated for cleerness in illustration; but 1n actual construction the latein! deliection of the :uch is very slight; Vpreferably f B end B are rigidly secured by a clamping- 'plnte E. F is a groove in the central rtion of the iug D, and G is a block edil); nhly secured in the roove F and notched ot H to form n. bearing for one end ofi-he :lrch element'C. 'The bottom of the groove F against whichl the block G bear` is pei-nl# lol to the plane. of the elements B ond l', so that :my adjustment of 4the. hlockrwill 'he exactly parallel to this pinne. Such ndjustment is effected h v e'scrcw engaging n threaded heel-ing in un angle flange E on the clun'lping plate E und hearing against the block (i in central nlinement with the arch member C. The hlock is ref- 'tnined in its position of odjushnent hy n clnmping;r screw J which )assos through o plante l( on the opposite side of the lug D :md through o slot D' in mid lug, und hns :l threaded engagement with the block (i. lVhen thel screw is hiosened the block G is free to swivel thereon und to rock on its point of' contact with the .screw I. there- .v permitting self-:dinoment with the end 'fief the element C to form n good h wing thereon.

elements and the hase-on which they are 'lhe opposite ends of the elementsi B lixed lane, and at the same time to permit o movement in 'this plane to compensate foranyelon' tion or contraction in the elements B an -B. To accomplish this without introducin frictional resistance the yoke L is cou ed to the bese by ambie unis' M, prefgmbly sta/nad te angle flanges B' at the ends of the elements B- and B. The; element C is attached to the-oke with a self-alinin bearing formed byv elf-shaped member `formingla notch for receiving the end of the arc and a pivotal connection N between this V-shaped member and the yoke. Thus both ends of ent with self-alini bearings, which insures full -,contact an facilitate the dissipatonof electrically' generated heat and to minimize the temperature rise.

The electrical circuitis closed and o cned 'by contact 4`and separation of the ar element C and a-coperatii contact 0. This contact must be adjusts. e for setting the redetermined initial distance from the arc member C, and it is important that it should, be maintained substantially at the center of the arch in all positions of adjustment thereof. I therefore preferabliy arran e the contact member O .upon an a j justabe arm P, which is pivotall connected` at Q to the member K. The ce end of the member P has secured thereto. a spring R which is notched to engage a screw S on the base A and operates to yieldably press rmifslf emplointga relatively wide strip r the element the member P in a 'direction away from the a T is an adjusting screw engaging a threaded bearing in the base A and having its free end in contact with the member P,

the arrangemcntbein such that said member P may be adjus 'by said screw against the tension of the spring R toward 'the arch member C. Also the member P being hinged at Q the member K will .be adjustc longitudinally to correspond with any .adjustment of the block G.

To prevent heat conduction to and from the base A. through theconnetions between the saine and the elements B and B, thermal insulation is employed in such connections. Thus, as shown, the links M have. arranged between the same and the buscan insulating material U, and there isarranged between the 1u D and the elements B and B the therm insulation `V. These insulating members will interpose-sufiicient resistance to the conduction of heat toavoid materially a'ecting the temperature of the ex ansiblc elements through the lag caused by t e mass of metal in the base A.

The construction of the parts being as described, they are casil assembled and when assembled are adjust or set for the desired i,eie,sei l operation. In this setting the screw J' is first loosened and the block Gr4 is ad'usted day operation of the set-screw I until e desired deflection Vor curvature of the arch member C is obtained. During this adjustment the block G is free to rock on the screw I so that its Vshaped notch H will be valined with the edgey of the end of the -member C, and a similar self-alinement will take tglace between the V-shaped'member'N and' e opposite end of the arch member. The adjustment ofthe screw I will also longitudinallyadjust the member' P b reason 'of its hinged connection Q with t e block K and screw J, thereby maintaining the contact O substantially at the centerof the arch. The screw J is then tightened to clamp the blocks G and K in their adjusted positions, after which the screw T may be adjusted to obtain cn desired spacing between the contactI O and the arch, according to the temperature at whichthe circuit is desired to close In operation the air of the room in which the instrument is located is free to come into contact with both faces of each of the elements B B and C, and as these elements are in substantially the same plane they will not in any way shield or interfere with each other. When there is a change in temperature causing either ex ansion or contraction of the elements B an B the yoke ends of said elements are free to move relativcto the base in their common planes by the Hexin of the link M. On the other hand a di erential expansion of the arch member C relative to said elements B and Bcan only result in a lateral deflection or change in curvature of the arch so as to ad'ust the same into or out of contact with t e contact4 member O. When contact is established whatever heat is electrically generated will be quickly distributed by conduction and dissipated through thc large air-exposed surface of the member C. As a consequence the opening and closing of the electrical circuit will correspond accurately to predetermined temperature changes in the air which bathcs the elements B B and C.

What I claim as my invention is: An electric contact thermostat, com rising an arch element, a pair of chord e ements arranged on opposite sides thereof and in substantially the same plane, a mountin or base for said elements having a pair of lugs projecting therefromfto w ich the correspending ends of said chord elements are secured, a yoke connecting the o posite ends of said chord elements, a iicxib e link connccting said yoke to said .mounting maintaining the plane of said elements while permittin lon itudinal adjustment in said plane, a b eck crming n bearing for the op- Vositr. ond of said arch clement arranged A ictwccn said lugs and having a bearing on iis Vsed mclmting parallel tojthe plane of said elements, a screw for adjusting said block to 'alter the curvature of the arch, a coperaling electrical contact member, en arm on mounted,

said bearing connection for the arch element for comtween said arm and pelling a and means in relaltion te space between ment.

In testimon cortesondng adjustment thereof,

for eterally adjusting said arm said mountmg to vary the thesamc and said arch elewhereof I ax m s ature. RY G. GEIS IN ER. 

